Generally, various processes such as film deposition, oxidization/diffusion, etching, annealing and the like are repeatedly carried out in order to fabricate semiconductor integrated circuits (IC). In order to improve process efficiency, a series of the above-mentioned processes are carried out while transferring the wafer from one process chamber after the next in a so-called cluster tool configured in a manner that process chambers for carrying out corresponding processes are coupled via a shared transfer chamber.
FIG. 11 is a schematic configuration view illustrating an example of a related-art process system. As shown, a process system 2 includes plural (e.g., four) process chambers 6A through 6D that are coupled via corresponding gate valves G to, for example, a shared transfer chamber 4 evacuatable to vacuum. The process chambers 6A through 6D are provided with corresponding susceptors 8A through 8D, an upper surface of which the wafer is placed on.
In addition, load-lock chambers 10A, 10B are coupled on one side to the shared transfer chamber 4 via corresponding gate valves G, and on the other side to a loader chamber 12 via corresponding gate valves G. Load ports 14 are provided on one side surface of the loader chamber 12, in order to load unprocessed wafers housed in a cassette and the like. Transfer mechanisms 16, 18 including pivotable and bendable/stretchable multiple-joint arms are provided in the loader chamber 12 and the shared transfer chamber 4. The transfer mechanisms 16, 18 hold and transfer the wafer W.
In this case, when holding and transferring the wafer W with the transfer mechanisms 16, 18, the wafer W needs to be precisely positioned in an appropriate position on forks 16A, 18A at distal ends of the transfer mechanisms 16, 18, and held without positional deviation. To this end, plural positional deviation detection sensors are provided in a fixed manner in the shared transfer chamber 4 in order to detect positional deviation of the wafer W held by the transfer mechanism 18 (Patent Documents 1 through 4).
Patent Document 1: Japanese Patent Application Laid-Open Publication No. H10-223732
Patent Document 2: Japanese Patent Application Laid-Open Publication No. H10-247681
Patent Document 3: Japanese Patent Application Laid-Open Publication No. 2002-43394
Patent Document 4: Japanese Patent Application Laid-Open Publication No. 2004-140147